Shoe for compressors

ABSTRACT

A shoe for compressors, in which lightening and practical strength can be made compatible with each other, is provided. A shoe for compressors, according to the invention, comprises a base portion having a swash-plate sliding contact surface in sliding contact with a swash plate and a semi-spherical portion made integral with the base portion and having a bearing-seat sliding contact surface in sliding contact with a bearing seat, which is in the form of a spherical surface and provided concavely on a piston. A cavity is formed between the base portion and the semi-spherical portion. The base portion and the semi-spherical portion are connected to each other by a solid connecting portion, which passes through centers of the both portions and extends in a central direction of the both portions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Patent Application No. 2006-251008 and Japanese Patent Application No. 2006-251012 both filed on Sep. 15, 2006, which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a shoe for compressors.

BACKGROUND OF THE INVENTION

In a compressor provided with a swash plate and a piston, a pair of longitudinal shoes for compressors can be provided between the swash plate and the piston. The respective shoes comprise a base portion and a semi-spherical portion made integral with the base portion. The base portion includes a swash-plate sliding contact surface in sliding contact with the swash plate. The semi-spherical portion includes a bearing-seat sliding contact surface in sliding contact with a bearing seat, which is provided concavely on the piston.

With the compressor constructed in the manner described above, a drive shaft rotates whereby the swash plate rotates synchronously and the piston reciprocates in a cylinder bore through the shoes. Thereby, suction, compression, and discharge strokes of refrigerant gas are performed on a head side of the piston. In the meantime, the swash-plate sliding contact surface of the base portion of the shoe comes into sliding contact with a surface of the swash plate and the bearing-seat sliding contact surface of the semi-spherical portion of the shoe comes into sliding contact with a bearing surface of the piston.

General shoes are semi-spherical in shape such that a base portion and a semi-spherical portion are solid and integral with each other. Generally, such shoes are manufactured by subjecting a wire material of, for example, SUJ2 (JIS G4805) to cutting, press working, polishing, etc.

On the other hand, shoes made lightweight by forming a cavity between a base portion and a semi-spherical portion are known (for example, JP-A-2005-90385, JP-A-2002-31051, JP-A-2-119686, JP-A-2002-39058, JP-A-2001-263225, JP-UM-A-6-40385). By using shoes of this kind for compressors, in which a swash plate can be changed in inclination, it is possible to decrease a reciprocating inertial force of a piston, thus enabling achieving an improvement in capacity controllability. Also, shoes of this kind can realize reduction in motive power for driving of a compressor, lightening of the compressor, etc.

With the conventional, known shoes described above, however, lightening is realized by a cavity but there is a fear with respect to practical strength.

That is, while suction, compression, and discharge strokes of refrigerant gas are performed in a compressor, a swash-plate sliding contact surface of a base portion of a shoe comes into sliding contact with a surface of a swash plate and a bearing-seat sliding contact surface of a semi-spherical portion of the shoe comes into sliding contact with a bearing surface of a piston. Therefore, a force acting in a direction, in which the base portion and the semi-spherical portion approach each other, acts much on the shoe.

The shoes disclosed in JP-A-2002-31051, JP-A-2-119686, JP-A-2002-39058, JP-A-2001-263225, or JP-UM-A-6-40385 described above are hard to sustain the force and there is a fear of deformation in a direction, in which the base portion and the semi-spherical portion approach each other, due to use over a long term. In this case, gap is generated between the swash plate and the base portion of the shoe, or between the semi-spherical portion of the shoe and a bearing seat of the piston to lead to generation of abnormal noise and an obstacle to smooth operation.

In this respect, it is thought that the shoe disclosed in JP-A-2005-90385 is improved as compared with the other shoes since the base portion and the semi-spherical portion are connected to each other by a hollow connecting portion, which passes through centers of the both portions and extends in a central direction thereof. Since the hollow connecting portion in this shoe is hollow, however, it is not possible as well to eradicate insufficiency in practical strength.

SUMMARY OF THE INVENTION

The invention has been thought of in view of the conventional situation and has its object to provide a shoe for compressors, in which lightening and practical strength can be made compatible with each other.

The invention provides a shoe for compressors, comprising a base portion having a swash-plate sliding contact surface in sliding contact with a swash plate and a semi-spherical portion made integral with the base portion and having a bearing-seat sliding contact surface in sliding contact with a bearing seat, which is in the form of a spherical surface and provided concavely on a piston.

In this shoe according to the invention, a cavity is formed between the base portion and the semi-spherical portion of the shoe. Also, in this shoe according to the invention, the base portion and the semi-spherical portion are connected to each other by a solid connecting portion, which passes through centers of the both portions and extends in a central direction of the both portions. Lightening of the shoe according to the invention is realized by the cavity formed between the base portion and the semi-spherical portion. Also, the shoe can ensure practical strength since the base portion and the semi-spherical portion are connected to each other by the solid connecting portion, which passes through centers of the both portions and extends in a central direction of the both portions, and the connecting portion sustains a force acting in a direction, in which the base portion and the semi-spherical portion are caused to approach each other.

Accordingly, the shoe according to the invention can make lightening and practical strength compatible with each other. Therefore, the shoe can perform effects of suppression of abnormal noise of a variable displacement type swash plate compressor, an improvement in durability, etc. in addition to effects of an improvement in capacity controllability of the compressor, reduction in motive power, lightening, etc.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which.

FIG. 1 is a cross sectional view showing a compressor, in which shoes according to Embodiment 1 to Embodiment 10 are used.

FIG. 2 is a cross sectional view showing an essential part of the compressor of Embodiment 1.

FIG. 3 is a cross sectional view showing the shoe of Embodiment 1.

FIG. 4 relates to a method of manufacturing the shoe of Embodiment 1, FIG. 4(A) being a cross sectional view showing a press die, etc. before hot forging, and FIG. 4(B) being a cross sectional view showing the press die, etc. after hot forging.

FIG. 5 is a cross sectional view showing a shoe of Embodiment 2.

FIG. 6 is a cross sectional view showing a shoe of Embodiment 3.

FIG. 7 is a disassembled, cross sectional view showing the shoe of Embodiment 3.

FIG. 8 is a cross sectional view showing a shoe of Embodiment 4.

FIG. 9 is a disassembled, cross sectional view showing the shoe of Embodiment 4.

FIG. 10 is a cross sectional view showing a shoe of Embodiment 5.

FIG. 11 is a disassembled, cross sectional view showing the shoe of Embodiment 5.

FIG. 12 is a cross sectional view showing a shoe of Embodiment 6.

FIG. 13 is a disassembled, cross sectional view showing the shoe of Embodiment 6.

FIG. 14 is a cross sectional view showing a shoe of Embodiment 7.

FIG. 15 is a perspective view showing the shoe of Embodiment 7.

FIG. 16 relates to a method of manufacturing the shoe of Embodiment 7, FIG. 16(A) being a cross sectional view showing a press die, etc. before hot forging, and FIG. 16(B) being a cross sectional view showing the press die, etc. after hot forging.

FIG. 17 is a cross sectional view showing a shoe of Embodiment 8.

FIG. 18 is a perspective view showing the shoe of Embodiment 8.

FIG. 19 relates to a method of manufacturing the shoe of Embodiment 8 and is a cross sectional view showing a press die, etc. after hot forging.

FIG. 20 relates to a shoe of Embodiment 9, FIG. 20(A) being a disassembled, cross sectional view, and FIG. 20(B) being a cross sectional view.

FIG. 21 relates to a shoe of Embodiment 10, FIG. 21(A) being a disassembled, cross sectional view, and FIG. 21(B) being a cross sectional view.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS Embodiment 1

First, a variable displacement type swash plate compressor will be described. With the compressor, a front housing 2 is joined to a front end of a cylinder block 1 and a rear housing 4 is joined to a rear end of the cylinder block 1 through a valve unit 3 as shown in FIG. 1. Axial holes 1 a, 2 a extending in an axial direction are provided through the cylinder block 1 and the front housing 2. A drive shaft 5 is supported rotatably by the axial holes 1 a, 2 a with bearing devices, etc. therebetween. In addition, lower and upper sides in FIG. 1 are defined as front and rear sides.

A crank chamber 6 is defined in the front housing 2. In the crank chamber 6, a lug plate 7 is fixed to the drive shaft 5 with a bearing device between itself and the front housing 2. A swash plate 8 formed on an outer peripheral side thereof with longitudinal, flat surfaces 8 a is provided rearwardly of the lug plate 7 in the crank chamber 6. The swash plate 8 has the drive shaft 5 extending therethrough and is varied in angle of inclination in this state by a link mechanism 9 provided between itself and the lug plate 7.

A plurality of cylinder bores 1 b extending in the axial direction are provided concentrically through the cylinder block 1. One-head pistons 10 are accommodated in the respective cylinder bores 1 b to be able to reciprocate therein. Neck portions are provided on side of the respective pistons 10 toward the crank chamber 6 and bearing seats 10 a in the form of a spherical surface are provided concavely on the neck portions of the respective pistons 10 to be opposed each other.

A pair of longitudinal shoes 21 are provided between the swash plate 8 and the respective pistons 10. As shown in FIG. 2, the respective shoes 21 comprise a disk-shaped base portion 211 and a semi-spherical portion 212 made integral with the base portion 211 and having a semi-spherical outer surface. An outer surface of the base portion 211 makes a circular swash-plate sliding contact surface 211 a in sliding contact with the swash plate 8. A peripheral edge of the swash-plate sliding contact surface 211 a is chamfered. The outer surface of the semi-spherical portion 212 makes a spherical bearing-seat sliding contact surface 212 a in sliding contact with the bearing seat 10 a of the piston 10.

As shown in FIG. 1, the rear housing 4 is formed with a suction chamber 4 a and a discharge chamber 4 b. The cylinder bores 1 b can be communicated to the suction chamber 4 a through a suction valve mechanism of the valve unit 3 and communicated to the discharge chamber 4 b through a discharge valve mechanism of the valve unit 3.

Also, a capacity control valve 11 is accommodated in the rear housing 4. The capacity control valve 11 is communicated to the suction chamber 4 a via a detection passage 4 c and causes an intake passage 4 d to provide communication or discommunication between the discharge chamber 4 b and the crank chamber 6. The capacity control valve 11 detects pressure in the suction chamber 4 a to change an opening degree of the intake passage 4 d to change a discharge capacity of the compressor. Also, an extraction passage 4 e provides communication between the crank chamber 6 and the suction chamber 4 a. A condenser 13, an expansion valve 14, and an evaporator 15 are connected to the discharge chamber 4 b through a piping 12, in order. The evaporator 15 is connected to the suction chamber 4 a through the piping 12.

A pulley 16 is provided rotatably at a front end of the front housing 2 with a bearing device therebetween, the pulley 16 being fixed to the drive shaft 5. A belt 18 rotationally driven by an engine 17 is wound round the pulley 16.

As shown in FIG. 3, cavity 213 is formed between the base portion 211 and the semi-spherical portion 212 of the shoe 21. Also, the base portion 211 and the semi-spherical portion 212 are connected to each other by a solid connecting portion 214, which passes centers of the portions and extends in a center direction of the portions.

The respective shoes 21 are manufactured in the following manufacturing method.

First, as shown in FIG. 4(A), a solid material W composed of, for example, an iron material SUJ2 (JIS G4805) is prepared in a material forming process. The material W includes a disk-shaped bottom portion W1, a disk-shaped umbrella portion W2 being coaxial with the bottom portion W1 and having a slightly smaller diameter than that of the bottom portion W1, and a shaft portion W3 extending in a central direction of the bottom portion W1 and the umbrella portion W2 to connect between the bottom portion W1 and the umbrella portion W2. The material W may be formed by casting, or formed by press working, or cutting.

A press die P composed of an upper die P1 and a lower die P2 is prepared in the process of press working. The upper die P1 is formed with a semi-spherically concave forming surface P11, which matches with the bearing-seat sliding contact surface 212 a of the shoe 21. The lower die P2 is formed with a forming surface P21, which matches with the swash-plate sliding contact surface 211 a of the shoe 21. A cavity C is defined by the forming surface P11 and the forming surface P21. As shown in FIG. 4(B), the material W is subjected to hot forging with the use of the press die P. Thereby, the bottom portion W1 of the material W makes the base portion 211, the umbrella portion W2 makes the semi-spherical portion 212 and the shaft portion W3 makes the connecting portion 214. Thus the shoe 21 according to Embodiment 1 is obtained.

According to the manufacturing method, it is possible to readily manufacture the shoe 21, of which the base portion 211 and the semi-spherical portion 212 are made of the same material. In addition, hot forging is also possible in multi-stage. Also, the shoe 21 can be also formed by subjecting a product after press working to surface polishing at need, or to tinning, surface coating such as DLC (Diamond Like Carbon), etc.

With the compressor constructed in the manner described above, the drive shaft 5 rotates whereby the swash plate 8 rotates synchronously and the pistons 10 reciprocate in the cylinder bores lb through the shoes 21. Thereby, compression spaces formed on head sides of the pistons 10 are varied in volume. Therefore, refrigerant gas in the suction chamber 4 a is sucked into the compression spaces to be compressed and then discharged into the discharge chamber 4 b. Thus a refrigerating action is performed in a refrigerating circuit composed of the compressor, the condenser 13, the expansion valve 14, and the evaporator 15. In the meantime, the shoe 21 brings the swash-plate sliding contact surface 211 a of the base portion 211 into sliding contact with the flat surface 8 a of the swash plate 8 and brings the bearing-seat sliding contact surface 212 a of the semi-spherical portion 212 into sliding contact with the bearing seat 10 a of the piston 10.

At this time, since the cavity 213 realizes lightening of the shoe 21, it is possible to decrease a reciprocating inertial force of the piston 10, thus enabling improving the compressor in capacity controllability. Also, the shoes 21 can realize reduction in motive power, by which the compressor is driven, lightening of the compressor, etc.

Also, the shoes 21 demonstrate a practical strength since the base portion 211 and the semi-spherical portion 212 are connected to each other by the solid connecting portion 214 and the connecting portion 214 sustains a force acting in a direction, in which the base portion 211 and the semi-spherical portion 212 approach each other.

Accordingly, since the shoes 21 enables making lightening and the practical strength compatible with each other, the shoes 21 make it possible to perform effects of suppression of abnormal noise of a variable displacement type swash plate compressor, an improvement in durability, etc. in addition to effects of an improvement in capacity controllability of the compressor, reduction in motive power, lightening of the compressor, etc.

Also, it is possible in the manufacturing method to perform a welding process of welding the base portion 211 and the semi-spherical portion 212. In this case, the base portion 211 and the semi-spherical portion 212 can be joined together firmly to appropriately bear a compressive reaction force, etc. in other regions than the connecting portion 214.

Embodiment 2

As shown in FIG. 5, opening 215 is formed on a shoe 22 of Embodiment 2 between a base portion 211 and a semi-spherical portion 212. The opening 215 is formed annularly round the base portion 211. The opening 215 communicates cavity 213 to an outside. The remaining construction is the same as that of the shoe 21 of Embodiment 1. The shoe 22 is used in the same compressor as that of Embodiment 1.

The shoe 22 is obtained by regulating the volume of the material W or the volume of the cavity C in the press die P in the manufacturing method of Embodiment 1.

With a compressor, in which the shoe 22 is used, a lubricating oil enters into the cavity 213 through the opening 215 and the lubricating oil is discharged outside from the opening 215 at need. Therefore, sliding contact between a swash-plate sliding contact surface 211 a of the base portion 211 and a surface 8 a of a swash plate 8, and sliding contact between a bearing-seat sliding contact surface 212 a of the semi-spherical portion 212 and a bearing seat 10 a of a piston 10 are made smooth. Thereby, the capacity controllability of the compressor, an effect of reduction in motive power, etc. are improved.

In addition, the opening 215 may be plural and formed in appropriate number by partially connecting the base portion 211 and the semi-spherical portion 212 to each other. Also, while the shoes 21, 22 use SUJ2 as a material therefor in Embodiment 1 and Embodiment 2, aluminum alloys such as Al—Si alloy, etc. may be used as a material of the shoes.

Embodiment 3

As shown in FIG. 6, with a shoe 23 of Embodiment 3, a material of a connecting portion 214 is different from a material of a base portion 211 and a semi-spherical portion 212. The remaining construction is the same as that of the shoe 21 of Embodiment 1. The shoe 23 is also used in the same compressor as that of Embodiment 1.

The shoe 23 is manufactured by the following manufacturing method.

First, as shown in FIG. 7, a hollow body W4 made of an aluminum alloy is prepared in a manufacturing process of the hollow body. The hollow body W4 is semi-spherical in external shape and includes a cavity 213 therein. An insertion port 216 is formed at a top of the hollow body W4 to communicate the cavity 213 to an outside.

In an assembling process, a solid shaft portion W5 made of SUJ2 described above is press fitted into the insertion port 216. Thereby, the hollow body W4 provides a base portion 211 and a semi-spherical portion 212 of the shoe 23 and the shaft portion W5 provides a connecting portion 214 of the shoe 23. Thus the shoe 23 of Embodiment 3 is obtained.

According to the manufacturing method, the shoe 23 can be made practical in strength by forming the connecting portion 214 from a highly stiff material. Also, in the embodiment, the shaft portion W5 may be produced from an aluminum alloy. Also, in this case, the shoe can be made high in strength by using the hollow body W4 intact as a shoe.

Embodiment 4

With a shoe 24 of Embodiment 4 shown in FIG. 8, a material of a semi-spherical portion 212 and a connecting portion 214 is different from that of a base portion 211. The remaining construction is the same as that of the shoe 21 of Embodiment 1. The shoe 24 is also used in the same compressor as that of Embodiment 1.

The shoe 24 is manufactured according to the following manufacturing method.

First, as shown in FIG. 9, a first member W6 made of SUJ2 is prepared in a first-member manufacturing process. The first member W6 includes a cap-shaped head portion W7 and a solid shaft portion W8 extending inside from a top of the head portion W7.

Also, a second disk-shaped member W9 made of an aluminum alloy is prepared in a second-member manufacturing process. A recess 217, into which a shaft portion W8 can be press fitted, is provided concavely on a center of the second member W9.

In an assembling process, a tip end of the shaft portion W8 of the first member W6 is press fitted into the recess 217 of the second member W9. Thereby, the head portion W7 of the first member W6 makes the semi-spherical portion 212 of the shoe 24, the shaft portion W8 of the first member W6 makes the connecting portion 214 of the shoe 24, and the second member W9 makes the base portion 211 of the shoe 24.

Embodiment 5

As shown in FIG. 10, with a shoe 25 of Embodiment 5, a material of a semi-spherical portion 212 is different from a material of a base portion 211 and a connecting portion 214. The remaining construction is the same as that of the shoe 21 of Embodiment 1. The shoe 25 is also used in the same compressor as that of Embodiment 1.

The shoe 25 is manufactured according to the following manufacturing method.

First, as shown in FIG. 11, a first cap-shaped member W10 made of SUJ2 is prepared in a first-member manufacturing process.

Also, a second member W11 made of SUJ2 is likewise prepared in a second-member manufacturing process. The second member W11 includes a disk-shaped bottom portion W12 and a solid shaft portion W13 extending vertically from a center of the bottom portion W12.

In an assembling process, a tip end of the shaft portion W13 is joined to a center of the first member W10 by means of friction welding or the like. Thereby, the first member W10 makes a semi-spherical portion 212 of the shoe 25, the bottom portion W12 of the second member W11 makes a base portion 211 of the shoe 25, and the shaft portion W13 of the second member W11 makes a connecting portion 214 of the shoe 25.

Embodiment 6

As shown in FIG. 12, with a shoe 26 of Embodiment 6, a material of a semi-spherical portion 212, a material of a base portion 211, and a material of a connecting portion 214 are different from one another. The remaining construction is the same as that of the shoe 21 of Embodiment 1. The shoe 26 is also used in the same compressor as that of Embodiment 1.

The shoe 26 is manufactured according to the following manufacturing method.

First, as shown in FIG. 13, a first cap-shaped member W14 made of an aluminum alloy is prepared in a first-member manufacturing process.

Also, a second disk-shaped member W15 made of a different aluminum alloy from that of the first member W14 is prepared in a second-member manufacturing process.

Further, a solid shaft portion W16 made of SUJ2 is prepared in a shaft-portion manufacturing process.

In an assembling process, one end of the shaft portion W16 is joined to a top of the first member W14 and the other end of the shaft portion W16 is joined to a center of the second member W15. Thereby, the first member W14 makes the semi-spherical portion 212 of the shoe 26, the second member W15 makes the base portion 211 of the shoe 26, and the shaft portion W16 makes the connecting portion 214 of the shoe 26.

With the shoe 26, materials of the base portion 211, the semi-spherical portion 212, and the connecting portion 214 are different from one another, so that freedom in choosing materials for a swash plate 8 and a piston 10 is widened to enable realizing a further excellent compressor. Also, by forming the connecting portion 214 from a highly stiff material, the shoe 26 can be made practical in strength.

Embodiment 7

As shown in FIG. 14, a shoe 31 comprises ribs 314 provided upright on a semi-spherical portion 312, an external surface of which is semi-spherical, on an opposite side of a bearing-seat sliding contact surface 312 a. A base portion 311 is constituted by a peripheral edge of the semi-spherical portion 312 and tip ends of the ribs 314. As shown in FIG. 15, the ribs 314 are formed to be cross-shaped to be equiangular at intervals of 90 degrees radially about centers of the base portion 311 and the semi-spherical portion 312. A solid connecting portion 314 a is formed centrally of the ribs 314. In this manner, a swash-plate sliding contact surface 311 a of the base portion 311 is defined by the ribs 314 and cavities 313 are provided between the ribs 314 provided upright on the semi-spherical portion 312. The shoe 31 is also used in the same compressor as that of Embodiment 1.

The respective shoes 31 are manufactured according to the following manufacturing method.

First, as shown in FIG. 16(A), a solid material W17 made of, for example, an iron material SUJ2 (JIS G4805) is prepared in a material forming process by press working or casting. The material W17 is substantially semi-spherical.

A press die P3 composed of an upper die P4 and a lower die P5 is prepared in the process of press working. The upper die P4 is formed with projections P41, which are used to form the ribs 314 on the shoe 31 and to form the cavities 313 between the ribs 314. Bottoms of the projections P41 define a forming surface P42, which matches with the swash-plate sliding contact surface 311 a. Also, the lower die P5 is formed with a forming surface P51, which matches with the bearing-seat sliding contact surface 312 a of the shoe 31. A clearance C1 is defined by the forming surfaces P42, P51. As shown in FIG. 16(B), the material W17 is subjected to hot forging with the use of the press die P3. Thereby, the material W17 is deformed by pressing forces in a vertical direction to provide the shoe 31 of Embodiment 7.

According to the manufacturing method, it is possible to readily manufacture the shoe 31, of which the base portion 311 and the semi-spherical portion 312 are made of the same material. In addition, hot forging is also possible in multi-stage. Also, the shoe 31 can be also formed by subjecting a product after press working to surface polishing at need, or to tinning, surface coating such as DLC (Diamond Like Carbon), etc.

Since the cavities 313 are provided between the ribs 314 on the back side of the semi-spherical portion 312, lightening of the shoe 31 can be realized. Therefore, it is possible to decrease a reciprocating inertial force of the piston 10, thus enabling improving the compressor in capacity controllability. Also, the shoes 31 can realize reduction in motive power, by which the compressor is driven, lightening of the compressor, etc.

Also, the ribs 314 of the shoe 31 sustains a force acting in a direction, in which the base portion 311 and the semi-spherical portion 312 are caused to approach each other. In particular, the connecting portion 314 a of the ribs 314 surely sustains the force. Therefore, the practical strength surely demonstrates itself even when a large force in a direction, in which the base portion 311 and the semi-spherical portion 312 in the compressor are caused to approach each other, acts much.

Accordingly, the shoes 31 enable making lightening and the practical strength compatible with each other and can be readily manufactured. Therefore, the shoes 31 make it possible to perform effects of suppression of abnormal noise of a variable displacement type swash plate compressor, an improvement in durability, etc. in addition to effects of an improvement in capacity controllability of the compressor, reduction in motive power, lightening of the compressor, etc. and to suppress an increase in manufacturing cost of the compressor.

Also, with the shoe 31, a lubricating oil in the compressor enters into the cavities 313 between the ribs 314 and the lubricating oil is discharged between the swash-plate sliding contact surface 311 a of the base portion 311 and the surface 8 a of the swash plate 8 at need, so that sliding contact there becomes smooth. Thereby, effects of an improvement in capacity controllability of the compressor, reduction in motive power, etc. are surely performed.

Embodiment 8

As shown in FIG. 17, a shoe 32 of Embodiment 8 comprises ribs 315 provided upright on a disk-shaped base portion 311 on an opposite side of a swash-plate sliding contact surface 311 a. Tip ends of the ribs 315 define a semi-spherical portion 312. As shown in FIG. 18, the ribs 315 are formed to be cross-shaped to be equiangular at intervals of 90 degrees radially about centers of the base portion 311 and the semi-spherical portion 312. A solid connecting portion 315 a is formed centrally of the ribs 315. In this manner, the bearing-seat sliding contact surface 312 a of the semi-spherical portion 312 is defined by the ribs 315 and cavities 313 are provided between the ribs 315 provided upright on the base portion 311. The remaining construction is the same as that of the shoe 31 of Embodiment 7. The shoe 32 is also used in the same compressor as that of Embodiment 1.

Since the cavities 313 are provided between the ribs 315 on the front side of the base portion 311, lightening of the shoe 32 can be realized by the cavities 313. Also, with the shoe 32, a lubricating oil in the compressor enters into the cavities 313 between the ribs 315 and the lubricating oil is discharged between the bearing-seat sliding contact surface 312 a of the semi-spherical portion 312 and a bearing seat 10 a of a piston 10 at need, so that sliding contact there becomes smooth. The remaining actions and effects are the same as those in Embodiment 7.

The respective shoes 32 are manufactured according to the following manufacturing method.

First, as shown in FIG. 19, a disk-shaped, solid material W18 made of SUJ2 is prepared in a material forming process by press working or casting. Also, a press die P6 composed of an upper die P7 and a lower die P8 is prepared in the process of press working. The upper die P7 is formed with a forming surface P71, which matches with the swash-plate sliding contact surface 311 a of the shoe 32. Also, the lower die P8 is formed with projections P81, which are used to form the ribs 315 on the shoe 32 and to form the cavities 313 between the ribs 315. Bottoms of the projections P81 define a forming surface P82, which matches with the bearing-seat sliding contact surface 312 a. A clearance C2 is defined by the forming surfaces P71, P82. The press die P6 is used to subject the material W18 to hot forging whereby the material W18 is deformed by pressing forces in a vertical direction to provide the shoe 32 of Embodiment 8. The manufacturing method also performs the same actions and effects as those of the manufacturing method in Embodiment 7.

Also, materials in Embodiment 7 and Embodiment 8 are not limited to SUJ2 but an aluminum alloy like Al—Si alloy may be used as the material.

Embodiment 9

As shown in FIG. 20(A), a shoe 33 of Embodiment 9 comprises a semi-spherical portion 316 and a base portion 317. The semi-spherical portion 316 includes a cap-shaped head portion 316 a having a bearing-seat sliding contact surface 316 c and ribs 316 b provided upright on the head portion 316 a on an opposite side of the bearing-seat sliding contact surface 316 c. The ribs 316 b are formed to be cross-shaped to be equiangular at intervals of 90 degrees radially about a center of the semi-spherical portion 316. A solid connecting portion 316 d is formed centrally of the ribs 316 b. The base portion 317 is disk-shaped to include a swash-plate sliding contact surface 317 b. Projections 317 a being fitted into tip ends of the ribs 316 b are protrusively provided on an upper surface of the base portion 317.

The semi-spherical portion 316 and the base portion 317 can be manufactured by press working or casting or the like. As shown in FIG. 20(B), in a process of fitting, the base portion 317 is fitted into the semi-spherical portion 316 while ensuring cavities 313 between itself and the semi-spherical portion 316. Thus the shoe 33 of Embodiment 9 is obtained.

A material of the semi-spherical portion 316 is SUJ2 and different from a material of the base portion 317, which comprises an aluminum alloy. The remaining construction is the same as that of the shoe 31 of Embodiment 7. The shoe 33 is also used in the same compressor as that of Embodiment 1.

Lightening of the shoe 33 is realized between the base portion 317 and the semi-spherical portion 316 by the cavities 313, which are ensured between the ribs 316 b. Also, since the base portion 317 is disk-shaped, it is possible to reduce a bearing pressure acting between the swash-plate sliding contact surface 317 b of the base portion 317 and a surface 8 a of a swash plate 8. Further, when openings are formed so as to communicate the cavities 313 to an outside, a lubricating oil in the compressor enters into the cavities 313 through the openings and the lubricating oil is discharged outside from the openings at need, so that sliding contact between the swash-plate sliding contact surface 317 b of the base portion 317 and the surface 8 a of the swash plate 8 and between the bearing-seat sliding contact surface 316 c of the semi-spherical portion 316 and a bearing seat 10 a of a piston 10 are made smooth. The remaining actions and effects are the same as those in Embodiment 7.

Also, in the manufacturing method, it is possible to perform a welding process of welding the base portion 317 and the semi-spherical portion 316 together. In this case, the base portion 317 and the semi-spherical portion 316 can be joined together firmly to appropriately bear a compressive reaction force, etc.

Embodiment 10

As shown in FIG. 21(A), a shoe 34 of Embodiment 10 comprises a base portion 319 and a semi-spherical portion 318. The base portion 319 is disk-shaped to include a bottom portion 319 a having a swash-plate sliding contact surface 319 c and ribs 319 b provided upright on the bottom portion 319 a on an opposite side of the bearing-seat sliding contact surface 319 c. The ribs 319 b are formed to be cross-shaped to be equiangular at intervals of 90 degrees radially about a center of the base portion 319. A solid connecting portion 319 d is formed centrally of the ribs 319 b. The semi-spherical portion 318 is cap-shaped to have a bearing-seat sliding contact surface 318 b. Projections 318 a being fitted into tip ends of the ribs 319 b are protrusively provided on an inner surface of the semi-spherical portion 318.

The base portion 319 and the semi-spherical portion 318 can be manufactured by press working or casting or the like. As shown in FIG. 21(B), in a process of fitting, the semi-spherical portion 318 is fitted onto the base portion 319 while ensuring cavities 313 between itself and the base portion 319. Thus the shoe 34 of Embodiment 10 is obtained.

A material of the base portion 319 is an aluminum alloy and different from a material of the semi-spherical portion 318, which comprises SUJ2. The remaining construction is the same as that of the shoe 31 of Embodiment 7. The shoe 34 is also used in the same compressor as that of Embodiment 1.

The shoe 34 also performs the same actions and effects as those in Embodiment 7.

Also, while the base portions 317, 319 of the shoes 33, 34 are made of an aluminum alloy and the semi-spherical portions 316, 318 are made of SUJ2 in Embodiment 9 and Embodiment 10, the base portions and the semi-spherical portions may be made of reverse materials to those in the former, or the both may be made of SUJ2 or an aluminum alloy.

In the invention, “solid” means that no hole is formed centrally of a shaft cross section, and is opposed to “hollow”, which means that a hole is formed centrally of a shaft cross section.

While the invention has been described on the basis of Embodiment 1 to Embodiment 10, it goes without saying that the invention is not limited to Embodiment 1 to Embodiment 10 but can be appropriately changed and applied within a scope not departing from the gist thereof.

In addition, the shoe, according to the invention, including a base portion, a semi-spherical portion, and a connecting portion can be manufactured by the following first to fifth manufacturing methods.

The first manufacturing method comprises a material forming process of obtaining a solid material and a press working process of using a press die to subject the material to press working to obtain a shoe. The shoe thus obtained includes a cavity formed between a base portion and a semi-spherical portion. Also, with the shoe, the base portion and the semi-spherical portion are connected to each other by a solid connecting portion, which passes centers of the base portion and the semi-spherical portion and extends in a central direction of the base portion and the semi-spherical portion.

According to the first manufacturing method, the material is deformed to make the shoe. According to the manufacturing method, it is possible to readily manufacture the shoe, of which the base portion and the semi-spherical portion are made of the same material. However, when an integral material, one end side and the other end side of which are made of different materials, is used in the first manufacturing method, it is possible to manufacture a shoe, of which a base portion and a semi-spherical portion are made of different materials. It is possible to adopt hot forging as press working.

In the first manufacturing method, an opening can be formed between the base portion and the semi-spherical portion by adjusting a volume of a material and a volume of the cavity in press working.

In the first manufacturing method, the material forming process can comprise a process of forming a disk-shaped bottom portion, a disk-shaped umbrella portion, and a shaft portion, which connects between the bottom portion and the umbrella portion. In this case, the process of press working uses a press die composed of an upper die and a lower die and subjects the umbrella portion to press working with the upper die while supporting the bottom portion on the lower die, whereby the bottom portion can make the base portion, the umbrella portion can make the umbrella portion, and the shaft portion can make the connecting portion.

The second manufacturing method comprises a hollow-body manufacturing process of obtaining a hollow body, which is semi-spherical in external shape and includes a cavity therein and is formed an insertion port to communicate the cavity to an outside at the top thereof, and an assembling process, in which the solid connecting portion is inserted into the insertion port such that the hollow body provides a base portion and a semi-spherical portion and the shaft portion provides a connecting portion, whereby a shoe is obtained. The shoe thus obtained includes the cavity formed between the base portion and the semi-spherical portion. Also, with the shoe, the base portion and the semi-spherical portion are connected to each other by the connecting portion, which passes centers of the base portion and the semi-spherical portion and extends in a central direction of the base portion and the semi-spherical portion.

According to the second manufacturing method, the hollow body provides the base portion and the semi-spherical portion of the shoe and the shaft portion provides the connecting portion of the shoe. In the second manufacturing method, it is possible to make a material of the shaft portion different from that of the hollow body. In this case, the shoe can be made further practical in strength by forming the connecting portion from a highly stiff material.

The third manufacturing method comprises a first-member manufacturing process of obtaining a cap-shaped head portion and a solid shaft portion extending inside from a top of the head portion, a second-member manufacturing process of obtaining a second disk-shaped member, and an assembling process, in which a tip end of the shaft portion is joined to a center of the second member such that the second member provides a base portion, the head portion provides a semi-spherical portion and the shaft portion provides the connecting portion, whereby a shoe is obtained. The shoe thus obtained includes a cavity formed between the base portion and the semi-spherical portion. Also, with the shoe, the base portion and the semi-spherical portion are connected to each other by the connecting portion, which passes centers of the base portion and the semi-spherical portion and extends in a central direction of the base portion and the semi-spherical portion.

According to the third manufacturing method, the head portion of the first member provides the semi-spherical portion of the shoe, the shaft portion of the first member provides the connecting portion of the shoe, and the second member provides the base portion of the shoe. In the manufacturing method, it is possible to readily manufacture a shoe, of which a semi-spherical portion, a connecting portion, and a base portion are made of different materials.

The fourth manufacturing method comprises a first-member manufacturing process of obtaining a first cap-shaped member, a second-member manufacturing process of obtaining a second member composed of a disk-shaped bottom portion and a solid shaft portion extending from a center of the bottom portion, and an assembling process, in which a tip end of the shaft portion is joined to a center of the first member such that the bottom portion provides a base portion, the first member provides a semi-spherical portion and the shaft portion provides the connecting portion, whereby a shoe is obtained. The shoe thus obtained includes a cavity formed between the base portion and the semi-spherical portion. Also, with the shoe, the base portion and the semi-spherical portion are connected to each other by the connecting portion, which passes centers of the base portion and the semi-spherical portion and extends in a central direction of the base portion and the semi-spherical portion.

According to the fourth manufacturing method, the first member provides the semi-spherical portion of the shoe, the bottom portion of the second member provides the base portion of the shoe, and the shaft portion of the second member provides the connecting portion of the shoe. According to the manufacturing method, it is possible to readily manufacture a shoe, of which a semi-spherical portion, a base portion, and a connecting portion are made of different materials.

The fifth manufacturing method comprises a first-member manufacturing process of obtaining a first cap-shaped member, a second-member manufacturing process of obtaining a second disk-shaped member, a shaft-portion manufacturing process of obtaining a solid shaft portion, and an assembling process, in which one end of the shaft portion is joined to a top of the first member and the other end of the shaft portion is joined to a center of the second member such that the second member provides the base portion, the first member provides the semi-spherical portion and the shaft portion provides the connecting portion, whereby a shoe is obtained. The shoe thus obtained includes a cavity formed between the base portion and the semi-spherical portion. Also, with the shoe, the base portion and the semi-spherical portion are connected to each other by the connecting portion, which passes centers of the base portion and the semi-spherical portion and extends in a central direction of the base portion and the semi-spherical portion.

According to the fifth manufacturing method, the first member provides the semi-spherical portion of the shoe, the second member provides the base portion of the shoe, and the shaft portion provides the connecting portion of the shoe. According to the manufacturing method, it is possible to readily manufacture a shoe, of which a semi-spherical portion, a base portion, and a connecting portion are made of different materials.

Preferably, the first to fifth manufacturing methods comprise a welding process of welding the base portion and the semi-spherical portion together. In this case, the base portion and the semi-spherical portion can be joined together firmly to appropriately bear a compressive reaction force, etc. in other regions than the connecting portion.

The shoe of the invention, in which a swash-plate sliding contact surface is defined by ribs, can be manufactured by the following sixth manufacturing method.

The sixth manufacturing method comprises a material forming process of obtaining a solid material and a press working process of using a press die to subject the material to press working to obtain a shoe. The shoe thus obtained includes a swash-plate sliding contact surface defined by ribs provided upright on a semi-spherical portion on an opposite side of a bearing-seat sliding contact surface.

According to the sixth manufacturing method, a material is deformed by pressing forces in one direction to provide the shoe. According to the manufacturing method, it is possible to readily manufacture the shoe, of which the swash-plate sliding contact surface and the semi-spherical portion are made of the same material. However, when an integral material, one end side and the other end side of which are made of different materials, is used in the sixth manufacturing method, it is also possible to manufacture a shoe, of which the swash-plate sliding contact surface and a semi-spherical portion are made of different materials. It is possible to adopt hot forging as press working.

In the sixth manufacturing method, the material forming process can comprise a process of forming a solid, semi-spherical material by means of press working or casting. In the press working process, a press die composed of an upper die and a lower die is used to support a material on the lower die, which matches a bearing-seat sliding contact surface, and to subject the material to press working with the upper die, which matches the ribs and the swash-plate sliding contact surface.

The shoe of the invention, in which a bearing-seat sliding contact surface is defined by ribs, can be manufactured by the following seventh manufacturing method.

The seventh manufacturing method comprises a material forming process of obtaining a solid material and a press working process of using a press die to subject the material to press working to obtain a shoe. The shoe thus obtained includes a bearing-seat sliding contact surface defined by ribs provided upright on a base portion on an opposite side of a swash-plate sliding contact surface. The seventh manufacturing method also performs the same actions and effects as those in the sixth manufacturing method.

In the seventh manufacturing method, the material forming process can comprise a process of forming a solid, disk-shaped material by means of press working or casting. In the press working process, a press die composed of an upper die and a lower die is used to support a material on the lower die, which matches ribs and a bearing-seat sliding contact surface, and to subject the material to press working with the upper die, which matches the swash-plate sliding contact surface.

Also, the ribs are not limited to a cross shape, in which four ribs are provided radially, but can be formed so that plural, that is, three or more ribs are provided radially.

Compressors, in which the shoes according to Embodiment 1 to Embodiment 10 are used, are not limited to the variable displacement type swash plate compressors described above but may comprise a fixed displacement type swash plate compressor. Refrigerant gas need not be R134a but may be carbon dioxide.

The invention can be made use of in air conditioners for vehicles. 

1. A shoe for compressors, comprising: a base portion having a swash-plate sliding contact surface in sliding contact with a swash plate, a semi-spherical portion made integral with the base portion and having a bearing-seat sliding contact surface in sliding contact with a bearing seat, which is in the form of a spherical surface and provided concavely on a piston, a cavity formed between the base portion and the semi-spherical portion, and a solid connecting portion, which connects the base portion and the semi-spherical portion to each other and passes through centers of the base portion and the semi-spherical portion and extends in a central direction of the base portion and the semi-spherical portion.
 2. The shoe for compressors, according to claim 1, further comprising an opening formed between the base portion and the semi-spherical portion to communicate the cavity to an outside.
 3. The shoe for compressors, according to claim 1, wherein materials of the base portion and the semi-spherical portion are different from each other.
 4. The shoe for compressors, according to claim 3, wherein materials of the base portion, the semi-spherical portion, and the connecting portion are different from one another.
 5. The shoe for compressors, according to claim 1, wherein the connecting portion is defined by a rib provided upright on the semi-spherical portion on an opposite side of the bearing-seat sliding contact surface and a tip end of the rib defines the swash-plate sliding contact surface.
 6. The shoe for compressors, according to claim 1, wherein the connecting portion is defined by a rib provided upright on the base portion on an opposite side of the swash-plate sliding contact surface and a tip end of the rib defines the bearing-seat sliding contact surface.
 7. The shoe for compressors, according to claim 1, wherein the semi-spherical portion includes a cap-shaped head portion and a rib provided upright on the head portion on an opposite side of the bearing-seat sliding contact surface, the connecting portion is defined by the rib, and the base portion is disk-shaped to fit with the semi-spherical portion such that the base portion and the semi-spherical portion ensure the cavity therebetween.
 8. The shoe for compressors, according to claim 1, wherein the base portion includes a disk-shaped bottom portion and a rib provided upright on the bottom portion on an opposite side of the swash-plate sliding contact surface, the connecting portion is defined by the rib, and the semi-spherical portion is cap-shaped to fit with the base portion such that the semi-spherical portion and the base portion ensure the cavity therebetween.
 9. The shoe for compressors, according to claim 7, wherein materials of the base portion and the semi-spherical portion are different from each other.
 10. The shoe for compressors, according to claim 8, wherein materials of the base portion and the semi-spherical portion are different from each other. 